There is most likely more than one area that needs attention.
You are a system of systems.
Yes, your psoas is probably an impacting factor.
Jill Miller Smashes Your Guts! (and psoas, and tacked down viscera, and matted down abdominals…) Part 2
Episode 301: Psoas Flossing and Biker Hips
Episode 290 Haiku Contest And Landing Position Part 1
Episode 290 Haiku Contest And Landing Position Part 2
Episode 129: The Twin Bowstrings, the Psoas and Scalenes
Episode 87: Hip Impingement 2: Band Variation
Episode 75: Your Inside Psoas Bits, World Record?
Episode 40: USAW Oly Prep: Some New Hip Love /Psoas/Calves
Episode 26: Hips and Seppuku: Psoas and Hip Soft Tissue Mob

You have missing range in your posterior chain.
Stretching and foam rolling is a first step. If you are not hitting the areas that are tight or restricted then these areas will not improve. You need to freestyle and hunt to find what needs work.
What you do prior to a workout would change based on what you are doing that day, your tight areas, and places of restriction that you have.